In a small bowl, whisk together 0.5 tablespoons of olive oil, lemon juice, lemon zest, minced garlic, dried oregano, sea salt, and black pepper to create the marinade.
Place the chicken breast in a shallow glass dish or a reusable silicone bag, pour the marinade over it, and let it marinate in the refrigerator for at least 30 minutes.
Preheat your grill or a cast-iron grill pan over medium-high heat until it is hot and lightly smoking.
Toss the asparagus spears and cherry tomatoes with the remaining 0.5 tablespoons of olive oil and a pinch of salt.
Place the chicken on the grill and cook for 6 to 7 minutes per side, or until the internal temperature reaches 165°F.
During the last 4 minutes of chicken cooking time, add the asparagus and cherry tomatoes to the grill, turning occasionally until tender and slightly charred.
Remove everything from the heat and let the chicken rest for 3 minutes before slicing.
Serve the sliced chicken and grilled vegetables over a bed of warm, fluffy quinoa.